DEVELOPMENT AND APPLICATION OF INNOVATIVE METHODS FOR THE DETERMINATION OF
CALCIUM CHANNEL BLOCKERS IN BIOLOGICAL SAMPLES
Calcium channel blockers, PT-SPE, MSPE, BAμE, CE, enantiomers, computational modeling.
The aim of this doctoral thesis was to develop and apply new analytical methods for the
determination of calcium channel blocking drugs (CCBs) in biological samples. The work
reported includes sample preparation protocols, namely pipette tip solid-phase extraction
(PT-SPE), magnetic solid phase extraction (MSPE) and bar adsorptive microextraction
(BAμE), followed by analysis by high-performance liquid chromatography, as well as a
chiral capillary electrophoresis (CCE) method. Regarding the use of PT-SPE and MSPE
techniques, sorbent materials based on polypyrrole (PPy) double-coated with hydrophilic
monomers (HMs) and proteins such as casein (CAS) and bovine serum albumin (BSA) were
developed, with the aim of excluding macromolecules present in the complex matrices. After
synthesis and characterization, the PPy-HM-CAS and MPPy-HM-BSA sorbents were
applied in the PT-SPE and MSPE techniques, respectively, for the determination of
nimodipine and nicardipine in breast milk and nifedipine and nimodipine in human plasma.
In both studies, after optimization of the preparation conditions, validation and application,
good recoveries, excellent protein exclusion capacity, adequate linearity, precision and
accuracy of the methods were demonstrated. In relation to the method involving BAμE,
commercial sorbent materials based on reverse phase polymers were successfully applied
for the determination of verapamil in water, plasma, urine and saliva samples, again
demonstrating good recoveries, adequate linearity, precision and accuracy, as well as a
matrix effect that does not limit the application of the method. Finally, the CCE method for
the enantioselective separation of amlodipine was optimized in terms of the composition,
concentration and pH of the background electrolyte, as well as the concentration of
carboxymethyl-β-cyclodextrin added as a chiral selector, obtaining separation efficiency and
good resolution between the enantiomers, identified through computational modelling
studies. It should be noted that the new analytical methods developed proved to be efficient,
robust and sustainable for the determination of CCBs, with potential applications in different
clinical and environmental contexts.